Take-down mechanism



Oct. 3, 1939. R. F. RAVEN E1- 2,174,948

TAKE-DOWN MECHANISM Filed Nov. 22, 1937 5 Sheets-Sheet 1 mmg lmmr K -PAV69 g 0 5 l/VVEA/TO/QS 57 Y r w 4 ATTORNEYS 1 @HHPaY w/e Oct. 3, 1939. R.F. RAVEN ET AL 2,174,943

CHANISM Filed Nov. 22, 1957 5 Sheets-Sheet 2 Fig,2.

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R. F. RAVEN ET AL TAKEDOWN MECHANISM Filed Nov. 22, 193'! 5 Sheets-Sheet3 HA 84 W01 N VE N 7095 ATTORNEYS Oct. 3, 1939. R. F. RAVEN El ALTAKE-DOWN MECHANISM Filed Nov. 22, 1937 5 Sheets-Shet 4 AW w w Q .m

m AAl @IW Oct. 3, 1939. R. F. RAVEN ET AL TAKE-DOWN MECHANISM Filed Nov.22, 1937 5 Sheets-Sheet 5- I I m 2 F. PA VEN 6 H 4. E4 y/we PatentedOct. 3, 1939 UNITED STATES PATENT OFFIQE TAKE-DOWN MECHANISM ReginaldFrank Raven,

Bceston, and Harry Avery Raynor, Wollaton Park, Nottingham,

England 11 Claims.

This application is a continuation-in-part of our co-pending applicationfiled September 16,

1936, Serial No. 101,140, for Corsets and like garments, and the presentinvention is for improvements in or relating to take-down or drawoffmechanism and is chiefly concerned with fabric take-down or draw-offmechanism suitable for use in knitting machines, although the inventionis not restricted in this respect for the mecham nism may be employed inother machines, such for example as looms. More specifically, however,it is an object of the invention to provide fabric take-down mechanism,of a simple construction, suitable for use with fabric the elasticity ofwhich l in the direction of its length, or its resistance todrawing-off, varies across its width, and the mechanism provided by thisinvention is designed for use in the production of comparativelysmalldiameter tubular fabric of this nature, such as tubular fabric forsurgical hose.

In the case of a small-diameter tube of fabric it is only practicable tolocate the entire fabricgripping mechanism outside the tube. From thisit follows that the tube must be flattened between the rollers that gripit, and this flattening in fact has no deleterious effect on the fabric.On the other hand the fact that the double thickness of fabric isgripped between the rollers, one roller making contact with the outerface of one layer of the fabric and the opposing roller making contactwith the outer face of the other layer, renders it highly desirable thatboth rollers shall be driven if the best results are to be obtained.

Therefore the present invention provides fabric take-down or draw-offmechanism, comprising a plurality of pairs of take-down rollers forengaging in their nips different portions in the width of the fabricbeing drawn-off, whereof the rollers of one pair are co-axial with therollers of the next pair but whereof the two rollers forming each pairare rotatable independently of those forming the next pair and areconnected together for rotation in opposite directions to pass thefabric through the nip between them, means for rotating each pair ofrollers, and means for automatically varying the speed of rotation, andtherefore the speed at which the fabric engaged by a pair of rollers isdrawn-off, in accordance with the linear rate of production, or theresistance to drawing oh. This mechanism is simple, and is eminentlywell suited for use in a circular knitting machine producing the elastictubular fabric of small diameter employed, without cutting-out to shape,for surgical hose or the like, in which machine the linear rate ofproduction varies as between different portions in the circumference ofthe tube (e. g., so that the fabric comes off the machine in a sinuousor curved form).

Conveniently, adjacent co-axial rollers are received on a spindle whichis common to them both, Two co-axial pairs of rollers will be foundsufficient for small diameter tubular fabric, and the provision of onlytwo pairs simplifies the driving mechanism, for each pair of rollersmust be driven independently of the other pair. Hence according to animportant subsidiary feature of the invention there are two pairs of theaforesaid rollers, and independent operating means for each pair islocated at the outer ends of the rollers (those ends of the co-axialrollers that are adjacent being regarded as the inner ends).

One roller of each pair must be rotated in a clockwise direction, andthe other in an anticlockwise direction looking from one end of themechanism. The best way of achieving this result, while employing twosimilar sets of operating means, is to apply the drive to the frontroller of one pair and the back roller of the other pair (for these tworollers rotate in the same direction when each is viewed from its outerend) and to transmit the drive thence to the other roller of each pair.

There may be for each pair of rollers operating means including ayieldable biassing device that is responsive to the resistance todrawing-off exerted by the fabric. More specifically, the said operatingmeans may include an oscillating driving member and means (e. g., thebiassing device aforesaid) for varying the amplitude of its oscillationsin accordance with the resistance to drawing-off exerted by the fabric.

This mechanism may comprise, for each pair of rollers, a ratchet wheel,a pawl, positive means for moving said pawl periodically in onedirection, and spring means for moving it in the other. Advantageouslythe spring means is arranged to move the pawl in its operative stroke.Therefore if the resistance exerted by the fabric to drawing off isgreater than the effort exerted by the spring upon the pawl the latteris rendered inoperative. That is to say (as will appear from aconsideration of the ensuing drawings and the appended description) ifthe resistance exerted by the fabric is too great to be overcome whollyor in part by the spring, the latter remains in a highlystressedcondition and prevents, wholly or in part, the movement of the pawl bythe said positive means and nullifies or modifies the action of saidpawl. Hence, if the resistance to drawing ofi varies as between twoportions in the Width of the fabric, one pair of rollers will continueto Operate to take up that portion of the fabric offering the leastresistance, while another pair of rollers remains stationary or operatesat a less speed. This permits the mechanism to be applied to a knittingmachine that produces a length of fabric which departs radically fromthe straight, for example fabric which is curved or is sinuous in form.

In order that the invention may be better understood reference will nowbe made to the accompanying drawings, in which Figure 1 shows a lengthof tubular fabric with constricted panels at intervals in its length andat diiferent parts of its circumference, it being in connection withknitting machines for producing such fabric that this invention isparticularly useful,

Figure 2 is an enlarged view of the fabric.

Figure 3 shows the main parts of one form of take-down or draw-offmechanism according to this invention,

Figure 4 is a plan view in greater detail of a preferred form of themechanism,

Figure 5 is an elevation thereof,

Figure 6 is a scrap View thereof, partly in section,

Figure 7 is an end view thereof,

Figure 8 is an elevation showing certain parts of a knitting machine forproducing the fabric shown in Figs. 1 and 2, and

Figure 9 is a plan view thereof.

By Way of example the improvement will be described as applied totake-down mechanism of the kind described in British patentspecification No. 357,323 wherein the fabric is taken down betweengripping rollers geared for opposite rotation and racked by pawl andratchet mechanism comprising a plurality (e. g., two) of ratchet wheelswith co-acting pawls spaced around a circle and each pawl being carriedby a pivoted arm which is rocked by the travelling engagement of aroller on said arm with a suitably disposed ring or race, theintermittent rocking of the pawl-carrying arms rotating the ratchets andfabric gripping rollers.

In this invention the opposed fabric gripping rollers (Fig. 3) aredivided in their length so as to provide two pairs of rollers 52, 52a,one pair 52 being rotated by one ratchet Wheel 53 and the other pair bya second ratchet wheel 54, the two pairs of rollers being axiallyaligned on loosely inserted spindle members 55. On the two rollerdriving spindles carrying the ratchets 53, 54, are pivotally mounted tworockers 56, 56a, each rocker carrying at one side of its pivot a rolleror its equivalent 5'! and having connected at the opposite side of thepivot a tension spring (biassing spring) 58 anchored to a relativelystationary part. Each rocker also carries a pivoted pawl 59, the twopawls coact- .ing with the ratchet wheels 53 and 54 respectively. Thesmall rollers 51 on the rockers 56, 56a extend beneath and are adaptedto coact with the under face of a ring or race which is fixed at asuitable inclination to the horizontal or is suitably shaped on itsunder face so that as the take-down mechanism rotates about a verticalaxis, the rockers 56, 5611 are, by virtue of the engagement of theroller elements 51 with said ring 60, pivotally displaced against theinfluence cf the springs 58 to lower the pawls 59 to the extent of oneor more teeth on the ratchets 53, 54, an opposite pivotal movement beingimparted to the rockers by the springs 58 to rack the ratchet wheels asthe rollers 51 travel to a higher part of the ring or race 60. It willbe appreciated that each time a ratchet is racked, the pair of fabricgripping rollers influenced by said ratchet are rotated to draw-off ortakedown the fabric. In this invention the strength or tension of thebiassing springs 58 is so determined that, should the resistance tostretch of the fabric in the direction of the stitch wales be greaterthan the force or effort exerted by a spring, said spring will betensioned and will be prevented from pivoting the rocker member toeffect a racking motion, whereas if the resistance exerted by the fabricbeing drawn off or taken down is insuificient to overcome the pull of arocker spring, said spring will pivot the rocker and in so doing rackthe draw-off rollers associated therewith. By this means when fabric isbeing taken down embodying constricted panels or portions A such as arehereinafter described with reference to Figs. 1 and 2, the resistance todraw-off exerted by that half or part of the circumference of the fabricembodying a constricted portion overcomes the influence of the rockerspring 58 and prevents H the appropriate pair of fabric gripping rollers52a from being rotated; whereas at the other half or part of thecircumference of the fabric the other pair of rollers 52 are racked totake down the fabric. Thus it will be appreciated that while the part Cof the fabric of a less constricted nature is being taken down at eachrevolution of the machine, the other part or half at which a constrictedpanel portion A is passing between the first-mentioned pair of rollers52a is taken down at a lesser speed seeing that said pair of rollers 52aare racked at less frequent intervals and will only be racked when theresistance to take-down has become sufficiently reduced to permit of therocker spring 58 operating the ratchet and rotating said pair of rollers52a.

If the fabric being taken down is of uniform or substantially uniformelasticity throughout its circumference in the direction of the walesthen the ratchets appertaining to both pairs of rollers 52, 52a will beoperated with equal frequency.

In the construction shown in Figs. 4 to 7 inclusive the cam ring isdivided into two semicircular portions Ella, 60b pivoted at 6| as shownin Fig. 5, oppositely inclined so that two racks are given to thetake-down mechanism for every revolution of the machine. The angle ofinclination of each half of the cam ring is adjustable, for eachhalf-ring is provided with a trunnion nut 54 that is screwed on to aspindle 62 depending from and rotatably mounted in the base 63 of themachine. A knob 65 is provided for rotating each spindle and associatedwith this knob there is an indicator 56 to facilitate the adjustment ofboth halves of the ring to the same angularity. Alternatively means maybe provided for simultaneously adjusting both halves. For example thetwo halves of the ring may be connected by convergent links (as in atoggle) to a common nut mounted on a spindle adjacent to the axis 6|.

In the arrangement illustrated it is convenient to provide a lock nut 61under each trunnion nut 64.

Each pair of take-down rollers 52 and 52a are threaded on loose spindles55 and near their ends are geared together by gears 68 and are mountedin brackets 69 depending from a part H! of the machine that rotates inrelation to the and, r

part 63. In order to facilitate the insertion of the fabric the rollersmay be moved apart by means of a lever H and mechanism substantiallysimilar to that described with reference to Fig. 4 of patentspecification No. 357,323. Screw means indicated at 12 may be providedfor adjusting the gap between the pairs of rollers in accordance withthe grip desired upon, or the thickness of, the fabric. It will benoticed that the rollers 51 on the rockers or truck levers 56 engage theupper surface of the cam ring 60 and are biased in a downward directionby springs 58.

There is a tendency for each pair of rollers to rotate in the reversedirection under the pull of the fabric. In order to prevent this asecond clawker or pawl I3 is associated with each ratchet wheel such as64 and is drawn into engagement with it by a spring 14.

It is pointed out that in each of the constructions hereinbeforedescribed, the pawl-andratchet driving mechanism for one pair of rollersis identical with that for the other pair, and that the drive is appliedto the front roller of one pair and to the back roller of the otherpair, and is thence transmitted to the other roller of each pair.

The application of the take-down mechanism to a knitting machine forproducing the fabric illustrated in Figs. 1 and 2 will now be describedwith reference to Figs. 8 and 9. These figures illustrate a circular ribknitting machine. This machine provided with two stitch thread feedersIt and H located at diametrically opposite positions and an elasticthread feeder l2 located intermediate of said stitch thread feeders. Thecylinder and dial needles of the machine are operated by knitting camsto draw loops from the two stitch threads l3 and M in oppositedirections and produce rib knitted fabric therefrom. The needlesappertaining to the cylinder and dial may be arranged in any suitablerib disposition, say for example 2 x 1. The elastic thread l5 fed at thefeeder I 2 is laid in between the oppositely drawn stitch loops so as tobe enclosed by them but not knitted. Advantageously the elastic threadI5 is fed under a suitable degree of tension between opposed truncatedconical rollers l6, the degree of tension being adjusted in any suitablemanner such as by raising and lowering the guides ll relatively to therollers [6 by rotation of a screw member it along which a bracket 69carrying said guides H is adapted to travel. The rotation of the feedrollers l6 and the consequent feeding of the thread i5 is effected fromthe needle cylinder through the intermediary of intermeshing gears 2i 2|and 22, the firstnamed gear 2% meshing, with a gear wheel rotating withthe cylinder, or alternatively with the cylinder needles so as to berotated thereby and the lastnamed wheel 22 being mounted On the axis ofone of the feed rollers It.

At one or more positions in the length of the tube or garment beingknitted a predetermined batch of successive or adjacent needles of oneset, less than the complete set, are rendered inactive at one of thestitch thread feeders, while at another position or positions in thecircumference of the tube or garment a different batch of successive oradjacent needles can be rendered inactive at the other stitch threadfeeder. Advantageously the batch or batches of needles rendered inactiveat predetermined times appertain to the cylinder needles, the fullcomplement of dial needles being continuously operated at each feed.Assuming for example that a surgical hose is being knitted such as isshown in Fig. 1, during the knitting of a panel portion A at the top andback of the calf or at the back of the knee, a batch of the cylinderneedles which would normally take thread and knit at said portion iscaused to miss at one feeder for several successive courses, all of theneedles meanwhile functioning to knit in the normal manner around theremaining part of the circumference of the fabric. As knittingprogresses the inactive cylinder needles are again brought intooperation and at another position in the length of the hose, say forexample at the instep portion, another batch of the cylinder needlesdiametrically opposed to the last named batch is temporarily renderedinactive at the second feeder so as to produce the panel B. This resultsin the elastic thread l5 being laid more frequently or being moreclosely pitched in the panel portions A and 13, thereby constricting thehose at these panel portions and shaping or curving same. During theknitting of the remaining part C of the hose the full complement of theneedles of both sets take thread and knit at both of the stitch threadfeeders.

The batch or batches of needles may be rendered inactive in numerousways, say for example by withdrawing a feeder from operation while saidbatch of needles passes the same, or by maintaining the needles in aretracted position so as not to take thread.

We claim:

1. Fabric take-down or draw-off mechanism, comprising a plurality ofpairs of rollers for engaging in their nips different portions in thewidth of the fabric being drawn ofi, whereof eac roller of one pair hasits axis parallel to the axis of a roller of the next pair, a supportfor the rollers, means connecting the two rollers of each pair togetherfor rotation in opposite directions, and driving means for each pair ofrollers, each of which driving means comprises a yielding member whichyields in response to resistance to rotation of said rollers.

2. Fabric take-down or draw-off mechanism, comprising a plurality ofpairs of rollers for engaging in their nips different portions in thewidth of the fabric being drawn off, each pair consisting of a frontroller and a back roller, means supporting the rollers with the axes ofthe front rollers in one plane and the axis of each of the back rollersparallel to the axes of the corresponding front roller in a planeparallel to said first plane, means connecting the front and backrollers of each pair together for rotation in opposite directions topass the fabric through their nip, and means for rotating each pair ofrollers independently, including means for automatically varying thespeed of rotation of one pair in relation to that of the remainder inresponse to variation in the resistance to take off.

3. Fabric draw-off or take-down mechanism, comprising a plurality ofindependently-rotatable pairs of draw-off rollers which pairs arearranged to engage different portions in the width of the fabric, saidwidth lying substantially in a plane, and the rollers constituting eachpair being connected together for rotation in opposite directions topass the fabric through the nip between them, a ratchet wheel connectedto a roller of one pair and another ratchet wheel connected to a rollerof the other pair, a pawl for moving each ratchet wheel to rotate theassociated rollers, means for intermittently moving said pawlsindependently of one another in the return direction of their stroke,and spring means for moving said pawls in the operative direction oftheir stroke.

4. Draw-off mechanism for drawing off a flat web of fabric comprisingtwo pairs of rollers, which pairs of rollers extend across differentportions in the width of the fabric being drawn off and have their nipslying substantially in a common plane, means connecting the rollers of apair together for rotation in opposite directions to draw said fabricflatly through thenips of the rollers in said plane, and operatingmechanism for each pair of rollers, which operating mechanism comprisesa ratchet wheel, a pawl co-operating therewith, spring means for movingsaid pawl in its operative stroke, and positive means for moving thepawl in its inoperative stroke and for simultaneously stressing saidspring means.

5. In a circular knitting machine for knitting tubular elastic fabricincluding local areas, extending over only a portion of thecircumference, which areas are of decreased elasticity or are producedat a lesser linear rate of production, draw-off mechanism for drawingoff the tube in flattened form which mechanism comprises a plurality ofpairs of rollers for accommodating between them the entire width of theflattened tube, at least one pair of which rollers receives the saidareas as the fabric passes from the needles, a support for the rollers,means connecting the two rollers of each pair together for rotation inopposite directions, and driving means for the rollers including meansfor driving said one pair independently of the other rollers, includingmeans for automatically changing the rate of drive of said one pair inresponse to change in those characteristics h-ereinbefore mentioned ofthe area taken down by said pair.

6. In the combination claimed in claim 5, an annular member within whichthe rollers are located, which member lies in a plane transverse to thedirection of take-off and to the axis of the machine, means foreffecting relative rotation about said axis between the rollers as awhole and said member, a part movable to and fro and connected to saidpair of rollers to drive them during its movement in one direction,means upon said annular member for moving said part in one directionupon the aforesaid relative rotation, and a spring for moving said partin the reverse direction.

'7. Fabric take-down or draw-off mechanism, comprising a plurality ofpairs of take-down rollers for engaging in their nips different portionsin the width of the fabric being drawn-off", whereof the rollers of onepair are co-axial with the rollers of the next pair but whereof the tworollers forming each pair are rotatable independently of those formingthe next pair and are connected together for rotation in oppositedirections to pass the fabric through the nip between them, and meansfor rotating each pair of rollers, including means for automaticallyvarying the speed of rotation, and therefore the speed at which thefabric engaged by a pair of rollers is drawn-off, in accordance with thelinear rate of production, or the resistance to drawing-off.

8. Mechanism according to claim 7, comprising spindles, each common toadjacent co-axial rollers and each having said adjacent co-axial rollersreceived thereon.

9. Fabric take-down or draw-off mechanism, comprising two pairs oftake-down rollers for engaging in their nips diiferent portions in thewidth of the fabric being drawn off, whereof the rollers of one pair arecoaxial with the rollers of the other pair but whereof the two r011- ersforming each pair are rotatable independently of those forming the otherpair, a support for the rollers, means connecting together the rollersforming each pair for rotation in opposite directions to pass the fabricthrough the nip between them, and independent operating means for eachpair of rollers, located at the outer ends thereof, for rotating saidrollers, including means for varying the take-up speed of each pair ofrollers in accordance with the. linear rate of production of that partof the fabric engaged by said pair.

10. Fabric take-down or draw-off mechanism, comprising a plurality ofpairs of rollers for engaging in their nips different portions in thewidth of the fabric being drawn off, each pair consisting of a frontroller and a back roller, means supporting the rollers with the axes ofthe front rollers in one plane and the axis of each of the back rollersparallel to the, axis of the front roller, means connecting the frontand back rollers of each pair together for rotation in oppositedirections to pass the fabric through their nip, an inclined annular cammember rotatable relatively to the rollers about an axis which issubstantially central of the length of the rollers and is normal to theroller axes, means for effecting said relative rotation, andspring-returned pawl-and-ratchet mechanism operated by said cam memberin its rotation to drive each pair of rollers independently, whichmechanism includes means for automatically varying the speed of rotationof one pair of rollers in relation to that of the remainder in responseto variation in the resistance of take-off.

11. Fabric take-down or draw-off mechanism, comprising a. plurality ofpairs of rollers for engaging in their nips different portions in thewidth of the fabric being drawn off", each pair consisting of a frontroller and a back roller, means supporting the rollers with the axes ofthe front rollers in one plane and the axis of each of the back rollersparallel to the axis of the front roller, means connecting the front andback rollers of each pair together for rotation in opposite directionsto pass the fabric through their nip, a cam-ring comprising two oppositeinclined halves, means for effecting relative rotation between said ringand rollers about an axis which is substantially central of and normalto the axes of the rollers, and means for rotating each pair of rollersindependently including pawland-ratchet mechanism operated by said ringin said relative rotation and means for automatically varying the speedof rotation of one pair of rollers in relation to that of the remainderin response to variation in the resistance to take-off.

R. FRANK RAVEN. H. A. RAYNOR.

